This application is a continuation-in-part of application Ser. No. 69,681 filed on July 6, 1987 which application is a continuation-in-part of application Ser. No. 841,925, filed on Mar. 20, 1986.
The invention is generally directed to a printer and a method of printing and in particular to a non-impact printer and printing method for printing characters and graphic images by transferring thermoplastic magnetic ink onto a transfer medium by application of heat and magnetic force.
A number of compact and low cost non-impact printers using magnetic ink have been proposed. Japanese patent publication No. 96541/77 discloses such a printing apparatus in which magnetic ink is used as the ink material for magnetic and thermal transfer of the melted ink. The magnetic attraction force produced by the magnet, which is separate from the heat supply or thermal head, acts on the ink to form the desired thermal images. Reference is made to FIG. 1 wherein a printer generally indicated as 120 in accordance with Japanese patent publication No. 96541/77 is depicted. Printer 120 includes a thermal head 121 which receives pulse signals indicative of dots to be printed. Thermal head 121 rests against magnetic ink medium 122 which includes a base film 123 and a thermoplastic magnetic ink layer 124. Thermoplastic magnetic ink 124 is allowed to contact transfer paper 125 during the time that thermal head 121 applies thermal energy to base film 123. After the ink 124 is melted in the appropriate locations magnet 126 rips the melted ink 124 off of base film 123 and onto transfer paper 125.
In prior art printers the magnetic ink medium 122 and transfer medium 125 are moved at a uniform speed relative to the thermal and magnetic heads. In other words, the relative speed between the magnetic ink medium 122 and the transfer medium 125 in the printing area between thermal head 121 and magnet 126 is zero. As a result, when printing is performed at very high speeds, insufficient amounts of the ink 124 are transferred onto transfer medium 125. Thus, the amount of ink actually transferred for each dot to be printed is quite small. This causes very light printing which has a generally inferior quality. In addition, because the contact area between the ink 124 and transfer paper 125 becomes quite small, such a printer has a disadvantage in that the ink must be capable of being easily torn off the ink medium which has the effect of reducing its adherence to the transfer paper.
When only the outlines of the printing data are to be printed on the transfer medium in a draft printing mode, the number of dots to be printed is generally reduced. While draft printing does not require the strong attractive force of the ink to the transfer medium as does the high quality printing, there is a need to reduce the consumption of the magnetic ink medium to minimize the cost of operating the printer.
Accordingly, there is a need for a high quality printer and method of printing characters and graphic images by transferring thermoplastic magnetic ink onto a transfer medium utilizing heat and magnetic force which produces high quality printing and is capable of minimizing use of the magnetic ink medium in a draft mode.